Electromagnetic pump



, L.H.ROLLER' ELECTROMAGNETI C PUMP April 17, 1934.

5 Sheets-Sheet 1 Filed May 7. 1928 INVENTOR Lou/S h! flo/ler I N8 NRIQ... S Q

A ORNEY April 17, 1934. L. H. ROLLER ELECTROMAGNETIC PUMP Filed May 7,1928 5 Sheets-Sheet 2 Q EEE Q I N wt INYENTOR A 011/: hf/Fol/errATTORNEY April 17, 1934. H. ROLLER ELECTROMAGNETIC PUIP Filed May 7,1928 5 Sheets-Sheet 3 I l I H. M 'I". IHIllllllllllllllllllllll bin" 3INVENTOR Lou/3 l1. fial/er." Y

A ORNEY A ril 17, 1934. L. H; ROLLER ELECTROMAGNETIC PUIP Filed llay 7,1928 5 Sheets-Sheet 4 April 17, 1934. ROLLER 1,954,831

ELECTROIAGNETIC PUIP Filed lay 7. 1928 5 Sheets-Sheet 5 INYENTOR Law: Ifflo/ler:

Patented Apr. 17, 1934 UNITED STATES PATENT orrics My invention relatesto pumps adapted for use in pumping either liquids or gases and has foran object to provide such a pump in which all moving parts arecompletely encased, thereby preventing 6 leakage of fluids by avoidingthe use of stumng boxes, packings, and like means.

With this object in view, I have invented an electromagnetically drivenpump which, in general, employs the principles of an electric motor,having a stationary or stator element and a moving element or armaturecorresponding to a "rotor which, however. reciprocates instead ofrunning continuously as in ordinary electric motors. In the preferredform of my invention, the armature has a rectilinear motion which may beconsidered as an angular motion about an infinitely distant center.

Another object of the invention is to provide an electric motor whichis, in itself, a pump; that is, one in which the stator is in the formof a cylinder and, in fact, forms part of a pump cylinder, while thearmature forms part of a plunger re ciprocating within the cylinder.Thus, instead of using a separate pump driven by a motor, the motor andpump are combined into a single integral machine.

The present invention is an improvement on that disclosed in my PatentNo. 1,647,147, issued November 1st, 1927 and an object of the presentinvention is to provide an electromagnetic pump having a more eflicientmotor portion.

A more specific object is to provide a straight line motor of theinduction type, but in which the armature is constructed to have ahigher electrical resistance and hence a higher force at the startingperiod of each stroke, thereby showing a higher efficiency.

Another object of the present invention is to provide anelectro-magnetic pump of very long stroke with respect to the diameterof the cylinder, so that the armature may operate at desirable speedsfrom the point of view of the electromagnetic action without operatingupon an excessive volume of fluid. Thus, I avoid using the ordinaryreduction gearing employed between a motor and a reciprocating pump.

Another obiect of the present invention is to provide for automaticallycutting off the electric power to the stator before the plunger hasreached the'end of its stroke, thereby eflecting a saving in currentconsumption and utilizing the pressure built up in the fluid beingpumped to arrest the plunger at the end of its stroke.

Another object of the invention is to store up a part of the energy ofcompression of the pump 14 Claims. (Cl. 173-240) and utilize this energyto overcome the inertia of the plunger on its return stroke.

Another object is to provide for internally cooling the motor portion ofthe pump by using a hollow plunger and extending a water-cooledtube fromhead to head of the cylinder through the plunger.

with these and other objects in view which will appear hereinafter, Ishall now describe a preferred embodiment of my invention and shall asthereafter define the novelty and scope of my invention in the claims.

In the accompanying drawings,

Fig. 1 is a plan view of my improved electromagnetic pump;

Fig. 2 is a front elevation of the same;

Fig. 3 is an end view on a larger scale looking from the right hand endof Fig. 2;

Fig. 4 is a fragmentary detail view in longitudinal section of thestator and armature; Fig. 5 is a fragmentary view partly in section andshowing the motor portion of the electromagnetic pump, the section beingtaken on the line 5-5 of Fig. 6;

Fig. 8 is a view in cross-section taken on the line 6-6 of Fig. 5 andviewed in the direction of the arrows;

Fig. 7 is a fragmentary detail view of a lamina used in the stator coreof the motor;

Fig. 8 is a detail view of a lamina used to convey magnetic flux througha water jacket employed on the pump;

Fig. 9 is a view in cross section taken on the line 9-9 of Fig. 5;

Fig. 10 is a plan view of a transformer used in the pump;

Fig. 11 is a view in transverse section taken on the line 11-11 of Fig.10;

Fig. 12 is a side view of the armature or plunger indicating therelative distribution of conductor rings thereon;

. Fig. 13 is a fragmentary side view partly in section of the right halfof the plunger, and Fig. 14 is a similar view of the left half of theplunger;

Fig. 15 is a view in longitudinal section through a portion of thearmature showing a means of cooling the same; and

Fig. 16 is a diagram of electrical connections.

The specific embodiment of my invention illustrated in the drawings is amachine particularly adapted for pumping liquid refrigerant such asammonia. In general, the machine is a horizontal double-actingelectromagnetic pmnp, and comprises a closed cylindrical casing in which0 tween the brackets and the pipe 30, as shown in Fig. 3. Similarly adischarge pipe 32 connecting opposite ends of the pump is carried on theopposite side of the base, being supported on insulating blocks 33carried by brackets 34 which are secured to the base 28. An inlet pipe35 communicates with one end of the suction pipe, and a delivery pipe 36leads from the center of the discharge pipe.

Motor section The motor section of the casing consists preferably of athin steel tube reinforced, if necessary, with rings of some suitableinsulating material. A fragment of the motor section is shown in Fig. 4.A steel tube is indicated at 40 and at suitable intervals thereon arereinforcing rings 41. The tube 40 'is preferably turned or otherwiseformed with annular depressions 42, as shown, in which the rings 41 areembedded. The purpose of these depressions will be explainedhereinafter. In practice, I find it advisable in forming this section ofthe casing, to place the steel tube on an arbor and then to wrap thetube with a continuous length of paper or cloth impregnated with asuitable phenolic compound. The cloth is of a width equal to the lengthof the tube, and the wrapping is continued until a thickness has beenbuilt which after subsequent treatment will provide the desired depth ofreinforcing rings 41. Then the tube and its wrapping may be compressedin a mold and subjected to suflicient heat to permanently set thephenolic compound. The tube with its coating is then placed in a lathe,and the coating is cut away at intervals down to the steel, leaving thereinforcing rings 41. A portion of the coating is leftuncut at each endof the tube, as indicated at 43, Fig. 5, while the extreme ends of thesteel tube are left bare. It will be understood that the tube is formedof very thin material and, in order to couple the motor section of thecasing to the intermediate cylinder sections, sleeves 44 are sweated onor otherwise secured upon the bare ends of the steel tube 40. Eachsleeve member 44 is threaded to screw into a tapped central bore of aspider 45. The spiders 45 provide means for anchoring the stator of themotor and also for coupling the motor section and the two intermediatecylinder sections, as will be explained hereinafter. The cylinder isbored true to receive the stator.

The stator The stator comprises a plurality of disk-shaped coilsindicated in Fig. 5 at 50. These coils are preferably formed asdescribed in my co-pending application, Serial No. 224,359, filedOctober 9, 1927, and consist of a continuous length of wire wound in twoor more layers with the termini of each coil at the outer periphery ofthe coil. Two such double coils as indicated in Fig. 4, are fitted overeach reinforcing ring 41. Fitted over the disk coils are-silicon steelcores 51 which are built up of comb-shaped lamina of silicon steel, asshown in Fig. 7, consisting of a back portion 51a and teeth 51b. Theteeth of the core members pass between the coils 50 and the rings 41 andcontact with the steel tube 40. Each core 51 is made up of a pluralityof lamina, as clearly shown in the Figs. 6 and 9. The back 51a of eachcombshaped lamina is provided with perforations 52 so that, inassembling the lamina into a core, they may be pinned together with pins53, preferably of non-conducting material (see Fig. 5).

The cores 51 are disposed radially about the tube 40 and are preferablymachined at their inner ends to fit the curvature of the tube. In theparticular embodiment illustrated, the cores are uniformly spaced 60apart, but the number and spacing of the cores may be varied as desired.The backs 51a of each set of core lamina are fitted into a. recess in ayoke 54. The latter is made rigid by suitable reinforcing ribs 55. Atsuitable intervals along each yoke, there are opposed pairs of flanges56 extending inwardly from opposite edges of the yoke, and through theseflanges pass the pins 53 which secure the core members to the yokes.Wedges 57 are fitted respectively on opposite sides of the cores betweenthe latter and the adjacent flanges 56 and screws 58 serve to draw thewedges radially outward. The wedges and flanges have co-acting taperedfaces so that by tightening the screws the lamina of each core aretightly clamped together. The yokes 54 are connected at each end toannular flange members 59 by means of bolts. As shown in Fig. 5, themotor unit is preferably made up of two or more sections connected bybolts 60 which pass through adjoining flange members 59 and the adjacentends of the yokes 54 while shorter bolts 61 connect the yokes to theouter flange members. The latter in turn are connected by bolts 62 tothe spiders 45, sleeves 63 on the bolts serving to space the flangemembers from the spiders.-

For convenience in assembling the stator and dismantling it forinspection and repairs, the flange members 59 are diametrically split toform upper and lower halves. Thus,- the upper or lower half of anysection of the stator may be removed by unbolting the correspondingflange members without disturbing the rest of the stator. The statorlamina are of unequal length so that alternate lamina will overlap atthe center of the stator unit and knit together with the adjoining endsof the lamina of the other stator section. The flange members 59 areeach formed with an inwardly projecting peripheral rim 64 and arepreferably polyhedral instead of circular in proflle, so as to reducebulk. Set screws 65 are threaded into the rims 64 and bear against theyokes 54. The bolt-holes in the flange members 59 through which thebolts 60 and 61 pass, are large enough to permit a certain amount ofplay, so that by tightening up the set screws 65 the yokes and the coremembers they carry may be adjusted relatively to the steel tube 40 andare preferably pressed tightly against said tube.

v The armature or plunger The armature or plunger of the motor unitconsists of a hollow steel shaft 70 on which are mounted metal rings ofhigh conductivity interspersed with metal rings of low electrical buthigh magnetic conductivity. The rings of high electrical conductivity 71(Figs. 4, 13 and 14) are preferably of copper throughout the main body 5of the plunger and are separated by rings 72 of say, silicon steel. Thecopper rings are approximately of twice the thickness of the steel ringsand there are preferably two narrow steel rings between each pair ofcopper rings. A length of the plunger approximately equal to the strokeof the pump, is fitted with copper rings, while, at either end of thearmature for a length equal to half that of the stator, the copper ringsare .replaced with rings 73 of lead or some metal ofiering a muchhigherelectrical resistance than copper. The relative arrangement of rings onthe armature is indicated in Fig. 12. Owing to its length, the shaft 70is preferably made in sections, each section having a tapped socket 74at one end and threaded stem 75 at the other by means of which thesections may be screwed together. At the center joint each section isfitted with a steel ring 76 afiixed thereon and providing an abutmentfor the conductor rings and spacers. Against these abutments, theconductor rings are clamped by end sections '77 of the shaft which arethreaded upon the outer stems of the center sections. Pins 78 serve tohold the sections from unscrewing. The end sections which are of adiameter equal to that of the rings, serve as pump plungers and areprovided with piston rings 79 fitted in suitable ring grooves.

Pump sections 0/ the cylinder The two end portions 26 of the casing(Figs. 1 and 2), as well as the intermediate connecting sections 27, aremade like the section 25, of a tube of thin steel 80 (Fig. 11)reinforced with a sleeve or rings. of some phenolic condensation product81. The motor section and the intermediate sections of the casing arethen bolted together with bearing or guide blocks 84, interposedtherebetween. These bearing blocks support the sliding plunger '70 andare slightly eccentric so as to raise the axis of the plunger slightlyabove that of the tubes 40 and 80. Hence, in operation, the magneticpull on the plunger will tend to lift the plunger against gravity, thusvirtually reducing its weight and wear on its bearings.

Similarly, the end or pump sections of the easing are coupled to theintermediate sections with valve blocks 86 therebetween and at each endof the pump there is a cylinder block 89.

The suction pipe 30 (Figs. 2 and 3) is provided with two valves 91 fromwhich pipes 92 lead into the two valve blocks 86 and with two valves 91Afrom which pipes 93 lead into the end or cylinder blocks 89. Thedischarge pipe 32 connects with the blocks 89 through a pair ofdischarge valves 94. Communicating with the interior of the pumpcylinder at each end of the machine is a short vertical pipe 95 which isadapted to be filled with air or gas and serves as an air dome or gaschamber to store energy for starting the plunger in the reversedirection. Similarly, a pipe 96 is connected to the discharge pipe 32adjacent each discharge valve 94 to serve as an air or gas chamber forsmoothing out the pulsations of the pump.

Passing from end to end of the machine through the hollow plunger andarmature shaft is a fixed pipe 105. The latter is sealed against leakageat each end of the cylinder. Water is circulated through this pipe tocool the pump internally. The plunger 70 runs freely on the pipe and toprevent transfer of fiuid from one end of the pump to the other throughthe bore of the plunger, piston rings 107 (Fig. 15) are seated on thepipe 105, near its middle, to engage and fit snugly against the plunger.The rings 107 are located within the motor section where most of theheat is generated, and provide a good path for the flow of heat into thewater pipe 105. When the pump is operated on liquids rather than gases,internal cooling will not generally be needed, and the pipe 105 may bewithdrawn, and the openings in the ends of the cylinder. as well asthose in the plunger, may be plugged up. In addition to the internalcooling, I provide a water jacket 108 (Figs. 10 and 11) about eachcylinder section of the pump, as will be described more fully below.

Transformers To control the reversal of the motor at the end of eachstroke, I provide a pair of open core transformers T-1 and T-2 near theleft-hand end of the machine, as viewed in Figs. 1 and 2. and a pair ofsimilar transformers T3 and T4 near the right hand end of the machine.The transformers are clamped on the water jacket and two of them, T-land T3, are located adjacent the intermediate blocks 88 and the othertwo adjacent the cylinder blocks 89. The construction of thesetransformers is shown in Figs. 10 and 11.

The water jacket 108 consists preferably in a thin tube of insulatingmaterial and, at the points where the transformers are applied, softiron laminae 111 are fitted radially about the cylinder serving to spacethe jacket 108 from the cylinder. These lamina: are comb-shaped, asshown in Fig. 8, being provided with teeth 112 which fit between therings 81 and contact with the thin steel tube 80. The laminae serve toprovide a good magnetic path through the water jacket to the tube 81while the water is free 'to circulam between the lamina: to carry offvthe heat developed by the pump.

The core 114 of each transformer is built up of U-shaped soft ironlamina! which are clamped together between plates 115 by means of bolts116. The free ends oi the core legs are shaped to fit snugly against thewater jacket 108.

Clamping plates 117 secured to the top and bottom of each core legembrace the water jacket and serve to clamp the core thereto, However,most of the weight of the transformer is carried by a bracket 118 whichis secured to the base 28 of the machine. Around one leg of thetransformer core is fitted a primary coil 120, and around the other asecondary coil 121. As will be explained more fully hereinafter, whenthe plunger 70 passes the core of a transformer, there is an increase incurrent induced in the secondary of the transformer and this current isemployed to control the motor through suitable relays.

Electrical connections The motor shown in the drawings is adapted forthree-phase alternating current. The coils 50 are arranged in threegroups a. b and c which are Y-connected to three power mains A, B and C,as indicated in Fig. 16. A three-pole switch 140 serves to control theadmission of power to the mains A, B and C. The motor is reversed in theusual manner, i. e., by alternately transposing the connections with thepower mains of two of the Y-branches of the stator coils, thus varyingthe phase relation of successive windings and causing a change in thedirection of travel of the arms.- ture. This reversal of the motor iseffected by means of a switch 8 which, in turn, is operated by a relay Rcontrolled by the transformers, as will now be explained. While the mainA is permanently connected to the a coils of the motor stator and thevalve stators, the mains B and C are connected with the other coilsalternately in the order b-c and c-b. The main Bis connected to contactarms 141 and 142 and main C to contact arms 143 and 144 of the switch S.Arms 141 and 143 are insulated from each other and are mounted on a rockshaft 145 while the arms 142 and 144 are insulated from each other andmounted on a rock shaft 146. The rock shafts 145 and 146 bear armatures147 and 148 respectively adapted to be actuated by electromagnets 149and 150. When the armature 147 is actuated by electromagnet 149, thearms 141 and 143 make contact with the terminals 151 and 152respectively which are connected to the windings c and b respectivelyand, when the armature 148 is attracted by electromagnet 150, the arms142 and 144 make contact with terminals 153 and 154 respectively whichare connected to the windings b and 0 respectively. Thus, energizing ofmagnet connects mains B and C to the b and c coils respectively, andwhile energizing magnet 149 reverses thefield by connecting the B and Cmains to coils c and b respectively.

Mounted on the shaft 145 is a contact arm 155 which is adapted to engagea contact point 156 connected by a line 156a to a terminal of theprimary winding P1 of the transformer of T1 when the electromagnet 149is energized. Similarly, shaft 146 bears a contact arm 157 which engagesa contact point 158 connected by wire 158a to a terminal of the primarywinding P3 of transformer T-3. The opposite terminals of the primarycoils P1 and P3 are connected together by a wire 159 which in turn isconnected through a resistance or reactance 160 and by a line 161 to themain B. The contact arms 155 and 157 are connected together and to aterminal of the magnet 150 by a line 162, and the latter in turn isconnected by a lead 1641) to the main A. A terminal of the magnet 149 isconnected by a line 163 to the main A. Interposed in the lead 163 is anautomatic switch 164 controlled by a thermostat. The automatic switchmay be shunted by throwing a switch 16411 which leads through a handswitch 163a, whenever it is desired to substitute hand control forthermostatic control. I

Springs 165 serve to resist the pull of electromagnets 149 and 150 onarmatures 147 and 148. Means are provided to prevent both arms 155 and157 from swinging out of vertical position should both electromagnets149 and 159 be energized simultaneously. Such means may consist of a bar166 having pin and slot connection with the arms 147 and 148. When saidelectromagnets are unenergized, the arms 155 and 157 press againstspring contact arms 167 and 168 respect vely, but are electricallyinsulated therefrom. The spring contact arms are thus pressed by thesprings 165 against terminals of a connecting line 168a. The contact arm167 is connected by a line 169 to one terminal of the primary coil P2 ofthe transformer T2, while contact arm 168 isconnected by the line 163 tothe main A. The other terminal of the coil P2 is connected by line 170,through the primary P4 of transformer T4 and by lines 171 and 172 to themain B. Thus, when, and only when, both of the magnets 149 and 150 arede-energized (i. e., when no current is passing through primaries P1 andP--3) a path for the flow of current is established across 1,954,881 thelead 168a and through the primaries P2 and P4. When current is being fedthrough either one of the primaries P1 and P -3, it cannot pass throughthe other because of the bar 166 which interlocks the arms 155 and 157.

The electromagnets 149 and 150 are controlled by the relay R which hasfour solenoids M1, M2, M--3 and M4. These solenoids are respectivelyelectrically connected to and energized by the secondaries S1, S2, S3and 8-4 of the transformers T1, T2, T3 and T4. The solenoids arearranged in opposed pairs M4 and M1 constituting one pair and M--2 andM3. the other. Operated by the solenoids M-4 and M1 is a contact arm 175which is electrically connected to a second arm 176 operated by theother pair of solenoids. The relay is of the type in which the contactarms cannot remain in a neutral position but are always either in one orthe other extreme position. The contact arm 175 is adapted to engage acontact 177 when actuated by the solenoid M1 and a contact 178 whenactuated by the solenoid M4. The contacts 177 and 180 are electricallyconnected to the line 172 and thence to the main B. Contact 178 isconnected to a terminal of the electromagnet 149 and contact 179 to aterminal of the electromagnet 150. As explained above, the oppositeterminals of the electromagnets 149 and 150, are connected by way oflines 163 and 164b respectively, to the main A.

Shunted across the contacts 153 and 154 is the solenoid 181 of a flutterrelay. A plunger 182 is adapted to make contact with a pair of contactpoints 183 and 184 connected respectively to the contacts 177 and 178.The solenoid, when eneris adapted to make contact with a pair of contactpoints 183 and 184. When the solenoid is deenergized, the plunger movescomparatively slowly and after an appreciable time interval, which maybe adjusted at will, it engages the con tact points 183 and 184providing a path for current across the contacts 177 and 178. The partwhich the flutter relay plays in the operation of the electromagneticpump will be explained hereinafter. Inserted in the line 15611 in serieswith the primary P1 is a relay coil 185, and an opposed relay coil 186is inserted in the line 15811 in series with the primary P-3. Thesecoils control a switch arm 187 which is connected to the line 170 andplays between a pair of contact points. One of the contact points isconnected through a resistance 188 by way of a shunt line 189 to theprimary P4 while the other is connected through a resistance 190 througha shunt line 191 to the primary P2. The purpose of these shunt lineswill be explained hereinafter.

Operation of the pump In the control of the motor, the transformers T1and T3 are used to cut off the current to the motor while thetransformers T2 and T4 are used to reverse the motor field. In thediagram, Fig. 16, the plunger 70 is shown in full lines in its extremeleft-hand position and the relay and switch parts are shown in thepositions they occupy as the plunger starts to travel from left toright. A moment previously, the plunger, by bridging the core legs ofthe transformer T2, provided an increased magnetic flux through the coreand hence induced an increased voltage in the secondary 8-2 whichenergized solenoid M2 and closed a circuit through the electromagnet150. ,This circuit may be traced from the main A through the line 164b,magnet 150, thence by way of'line 179', contact 179, arm 176, arm 175,

'contact 177, and line 172 to main B. As soon that the am 157, byengaging contact 158, has

established a circuit through primary P3. This circuit may be traced asfollows: from the main A, line 1641), line 162, arm 157, contact 158,line 158a, coil 186, to the primary P-3, thence by way of reactance 160and lines 161, 171 and 172 to the main B. The parts are now in theposition indicated in the diagram Fig. 16 with only one transformerprimary energized (namely P-3), and the motor stator windings are soconnected as to exert a force on the plunger 70, urging the lattertoward the right.

In series with the primary P3 is the relay 186 so that the switch arm187 is swung to the position shown in full lines when said primary isenergized, thereby closing the line which shunts the primary oftransformer T2. However, no current fiows through either of thetransformers T-2 or T-4 until both spring arms 167 and 168 have beenactuated to close the circuit through the line 1680.

After the plunger has traveled to the right sufficiently to enter themagnetic circuit of the transformer T3,'there will be a sudden increaseof magnetic flux flowing through the transformer core with acorresponding increase of voltage induced in the secondary 8-3. Theincreased voltage will be sumcient for the solenoid 16-3 to attract thearm 176 to the position indicated by broken lines in the diagram.thereby interrupting the circuit through solenoid 150. Thereupon thespring 165, acting on armature 148. turns the shaft 146 withdrawing theswitch arms 142 and 144 from contacts 153 and 154 respectively andbreaking the circuit from mains B and C to wind:

ings b and c respectively. The stator is thus de- 1 energized and theplunger continues under its own momentum. At the same time, the arm 157interrupts the circuit through the primary P-3 and, by pressing the arm168 against the lead 168a re-establishes the circuit through the twoprimaries P-2 and P-4. Most of the current is by-passed through theshunt circuit around primary P2 and hence primary P-4 is more stronglyenergized than primary P-2. However, little power is consumed by thetransformer T-4 until the plunger enters the magnetic field of primaryP-4. Thereupon there will be a sudden increase of voltage induced in thesecondary 8-4 which will cause the solenoid M.-4 to draw the arm 175 tothe position shown by broken lines. In this position, a circuit isestablished through electromagnet 149 which may be traced as follows:from main A through switches 164a, thermostatic switch 164, line 163,electromagnet 149, contact 178, arms 175 and 176, contact 180 and line172 to main B. The electromagnet 149 attracts the armature 147 turningthe shaft 145 on its axis and moving the parts carried thereby to thepositions indicated by broken lines. As soon as the arm 155 leaves thecontact arm 167, the circuit through the primaries P-4 and 1'-'2 isbroken In the new position of the shaft 145, the arms 141 and 143 engagecontacts 151 and 152 respectively, so that the main B is now connectedwith the c coils and the main C with the b coils of the motor and valvestators. The stator fields are thus reversed and the plunger is moved inreverse direction or toward the left. Energizing .80 the electromagnet149 also serves to swing the contact arm 155 into engagement with thecontact 156 thereby closing the circuit of primary P-l, which may betraced from main A through lines 164D and 162, contact arm 155, contact156, line 156a, relay 185, primary P-1, lines 159 and 161, reactance160, and lines 171 and 172 to main B. Energizing of the relay 185 throwsthe switch 187 to the dotted line position shunting the primary P-4.Now, when the plunger enters the magnetic field of the transformer T-l,it causes an increase of induction in the secondary 8-1 which energizessolenoid 111-1 and attracts the arm 175 to the position shown by fulllines in the diagram. The circuit through electromagnet 149 is therebyinterrupted and the switch shaft 148 with the parts it carries returnsto the position slown in the diagram, breaking the stator circuitsthrough switch arms 143 and 144, while the arm 155 acting on contact arm167, re-establishes 10 the circuit through the primaries P-2 and P-4,but relatively little current will pass through primary P4 because ofthe shunt circuit established by throwing the switch 187 to the lefthand position.

The plunger now coasts to the end of its lefthand stroke and on enteringthe magnetic field of transformer T-2 causes an increase of voltage tobe induced in the secondary 8-2 which-energizes solenoid M-2 and swingsthe contact arm 176 to the position shown by full lines. The parts arethus restored to their initial position and the cycle of operations isrepeated as long as current is fed to the motor.

It will be observed that the shunt circuits controlled by the switch 187serve to weaken the primary of the end transformer from which theplunger is moving.

The flutter relay shunted across the contacts 177 and 178 prevents theplunger from stalling in a position intermediate between one of thestopping transformers T1 or T-3 and the adjacent field reversingtransformer T-2 or T-4. Thus, let us assume that the plunger had notsufilcient' momentum to reach the end of its stroke and that the partshave stopped with the right-hand end of theplunger located midwaybetween transformers T--3 and T-4; The switch arms 142 and 144 will haveswung open. interrupting current to the stator windingsfrom mains B andC. and simultaneously tie-energizing solenoid 181.- But the plunger-182will move down comparatively slowly until it bridges the contacts 183and 184. This will establish a momentary circuit through theelectromagnet 149, 185 which may be traced as follows: from main Athrough line 163, electromagnet 149, contacts 184 and 183, and line 172to main B. This will throw the switch arms 141 and 143 into closedposition supplying the stator windings with current, but reversing thefield so that the plunger will start backward or toward the left. But assoon as the stator windings are connected to the mains, the solenoid 181will be energized, breaking the circuit through electromagnet 149 andinterrupting the stator circuit. Thus, the flutter relay will continueto operate intermittently until the plunger has been drawn to theextreme left. when the transformer T-2 will act in the manner abovedescribed to close the relay switch arms 16o to best advantage.

142 and 144 and start the plunger on righthand stroke. The samerestorative service will be performed by the flutter relay should theplunger stall on its left-hand stroke with its lefthand end midwaybetween the transformers Tl and T2. The flutter relay will cause theplunger to be fed by steps toward leftuntil it reaches the reversingtransformer T--2.

By using two sets of transformers, one to cut oil the stator current andthe other to t en the current and simultaneously reverse the field, Iefiect a considerable saving of power. The transformers T-1 and T--3 areplaced where they will cut off the stator current at the proper momentto utilize the momentum of the plunger after the armature speeds up tonormal. In the present machine, a resistance is provided, as in- Idicated above, by employing lead rings in place of copper ateach end ofthe armature section of the main plunger 70. The parts are soproportioned that/when the plunger is in its extreme position either tothe right or left, half of that portion of the plunger which lies withinthe stator bears lead rings and the other copper rings. This proportioncould be varied to suit different conditions, but I have found thatequal parts of copper and lead in the armature at starting give a highlyeflicient result. Thus, at the time when the greatest force is required,the greatest amount of electrical resistance is present in the armatureand as the plunger moves, the resistance is proportionately cut down orremoved from the influence of the stator field until it is alleliminated. The resistance forms a permanent part-of the armature andyet the latter,

because it reciprocates instead of rotating, itself introduces andwithdraws the resistance as required, and the use of elaborate startingapparatus is avoided. The motor is so designedthat before thelead-ringed section at the opposite end of the plunger has entered thestator field, the current will be cut off from the stator and theplunger will coast under its own momentum to the end of its compressionstroke.

By cutting down the thickness of the tube 40 at the points 42,resistance is offered to the passage of magnetic flux along the tubefrom tooth to tooth of the core members, and most of the flux passesthrough the armature at the same time the tube is reinforced at saidpoints by the rings 41 and will withstand considerable internalpressure.

Having thus described my invention, and with the, understanding that Iam at liberty to make such alterations, modifications and variations indetails of construction and arrangements of parts as fall within thespirit and scope of my invention, what I claim and desire to protect byLetters Patent is:

1. A reciprocating electromagnetic motor comprising coils for producinga magnetic field. an armature actuated thereby, meanselectro-magnetically controlled by said armature-for automaticallyreversing the field at predetermined intervals to cause reciprocation ofthe armature and for interrupting the field during a part of each strokeof the armature.

2. A reciprocating electromagnetic motor, comprising coils for producinga magnetic field, an

armature actuated thereby, means electro-magnetically controlled by thearmature for periodically reversing the field to cause reciprocation ofthe armature and for automatically interrupting the field at apredetermined interval prior to each reversal of the field.

3. A reciprocating electromagnetic motor, com prising coilsfor'producing a magnetic field, an armature actuated thereby, areversing switch controlling the field, means electro-magneticallycontrolled by the armature for periodically operating the switch toreverse the fieldand the direction of motion or tne armature,and meanselectro-magnetically controlled by the armature for operating the switchto interrupt the field at a predetermined interval prior to eachreversal of the field.

4. An electromagnetic pump comprising a cylinder, a plunger reciprocabletherein, field coils adapted to produce a magnetic field for actuatingthe plunger, a reversing switch controlling the field, a pair of switchoperating coils, the plunger being adapted to enter said coilsrespectively, near opposite ends of its stroke and thereby cause currentvariations in the coils for operating said switch to alternately reversethe field, a second pair of coils located intermediate the switchoperating coils and also adapted to be alternately entered by theplunger to cause current variations therein, and means controlled bysaid last mentioned current variations for operating said switch tointerrupt the field.

5. An induction motor comprising a stator and an armature adapted to bereciprocated thereby, the armature being provided with coils of higherelectrical resistance at each end than in the middle in order togenerate a higher starting force atthe beginning of each stroke of thearmature.

6. A polyphase straight line motor comprising stator coils for producinga magnetic field, an armature actuated thereby, the armature beingprovided at each end thereof with coils of high electrical resistanceand with intermediate coils of low electrical resistance, meanscontrolled by the armature for interrupting the field before the highresistance armature coils have entered therein whereby the armature willcontinue under its own momentum, and means also controlled by thearmature for re-establishing the field, after the high resistancearmature coils have entered therein, but with the stator coils inreversed phase relation to exert a force in reverse direction on thearmature.

7. An electromagnetic pump comprising a cylinder of magnetizable metal,a plunger reciprocable therein, a plurality of field coils surroundingthe cylindencore members overlying the coils and formed with legsdisposed between the coils and engaging the cylinder, the cylinder wallbetween the core legs being of reduced thickness, and rings ofinsulating material applied to the cylinder to reinforce the parts ofreduced-thickness.

8. An electromagnetic pump comprising a cylinder, a hollow plungerreciprocable therein, field coils surrounding the cylinder and adaptedto actuate the plunger, a fixed cooling pipe within the plunger andopening out of one end of the cylinder, and cylinder rings between thepipe and the hollow interior of the plunger.

9. A reciprocating electro-magnetic motor comprising coils for producinga magnetic field, an armature actuated thereby, means for automaticallyreversing the field at predetermined intervals to cause reciprocation ofthe armature, means for interrupting the field during a part of eachstroke of the armature, and means for preventing stalling of thearmature while the field is interrupted.

10. A reciprocating electro-magnetic motor comprising coils forproducing a magnetic field, an armature actuated thereby, a pair ofswitches for reversely controlling said field whereby the field producedon closing one of the switches will be reversed with respect to thefield produced on closing the other of the switches, meanselectro-magnetically controlled by said armature for alternately closingsaid switches, and means also controlled by the armature for openingeach closed switch at a. predetermined time interval before the otherswitch is closed.

11. A reciprocating electro-magnetic motor comprising coils forproducing a magnetic field, an armature actuated thereby, a pair ofswitches for reversely controlling said field whereby the field producedon closing one of the switches will be reversed with respect to thefield produced on closing the other of the switches, meanselectromagnetically controlled by said armature for alternately closingsaid switches, means also controlled by the armature for opening eachclosed switch at a predetermined time interval before the other switchis closed, and means for preventing simultaneous closing of bothswitches.

12. An electro-magnetic motor comprising a cylinder, a plungerreciprocable therein, field coils adapted to produce a magnetic fieldfor actuating the plunger, a pair of switches for reversely controllingsaid field whereby the field produced on closing one of the switcheswill be reversed with respect to the field produced on closing the otherof the switches, means electromagnetically controlled by said plungerfor alternately closing said switches, and means alsoelectro-magnetically controlled by said plunger for opening each closedswitch at a predetermined interval before the other switch is closed.

13. An electro-magnetic motor comprising a cylinder, a plungerreciprocable therein, field coils adapted to produce a magnetic fieldfor actuating the plunger, 2. pair of switches for reversely controllingsaid field whereby the field produced on closing one of the switcheswill be reversed with respect to the field produced on closing the otherof the switches, means electro-magnetically controlled by said plungerfor alternately closing said switches, means also electro-magneticallycontrolled by said plunger for opening each closed switch at apredetermined interval before the other switch is closed, and means forpreventing simultaneous closing of both switches.

14. A reciprocating electro-magnetic motor, comprising a cylinder, 9.plunger fitted therein, field coils adapted toproduce a magnetic fieldfor actuating the plunger, means controlled by the plunger torperiodically reversing the field, whereby the plunger will bereciprocated in the cylinder, and means for retaining fiuid pressure inthe cylinder at the end of each stroke to aid in overcoming inertia ofthe plunger upon the starting of the next stroke.

LOUIS H. ROLLER.

